1. Technical Field
The present invention relates to a semiconductor device, a circuit substrate, an electro-optic device, and an electronic appliance.
2. Related Art
A semiconductor device such as an Integrated Circuit chip, etc. is mounted on a substrate of a circuit substrate or a liquid crystal display device that is mounted on various kinds of electronic appliances. For example, in a liquid crystal display device, an IC chip for driving liquid crystal designed to drive a liquid crystal panel is mounted on the glass substrate (opposing substrate) that composes the liquid crystal panel (so called Chip On Glass structure). When mounting the IC chip using a hard silicon substrate on a hard glass substrate, it is difficult to absorb the warpage of the IC chip as well as the glass substrate. Therefore, bump (projection) electrodes are formed on the IC chip, and the IC chip and the glass substrate are conductively connected by mounting the bump electrodes on the glass substrate while squashing them.
In recent years, there has been an increasing demand for smaller sized IC chips, while the number of IC chip terminals has increased as the liquid crystal display devices are achieving a highly integrated quality. Thus, there is a need to narrow the bump electrode pitch formed on the IC chip. It has been a usual practice to form bump electrodes by depositing an Au electroplate on a resist opening. Therefore, in order to narrow the pitch of bump electrodes, there has been a need to increase the aspect ratio of the resist opening. Hence, with known bump electrodes, it has been difficult to cope with the narrowing of the bump electrode pitch.
As a solution, a resin bump electrode 10 as shown in FIG. 9 has been developed. The resin bump electrode 10 has a conductive film 20 on the surface of a resin projection 12, where the conductive film 20 is connected to an electrode pad 24 of an IC chip 21. For example, refer to Japanese Unexamined Patent Publication No. H2-272737. When this resin bump electrode 10 touches the opposing substrate, the resin projection 12 deforms itself elastically. Hence the warpage of the IC chip 21 as well as of the opposing substrate can be absorbed. Moreover, there is no need to have a large aspect ratio, thus it is possible to cope with the narrowing of the bump electrode pitch.
The operation check of electronic elements (not shown) such as transistor and the like that compose the IC chip 21, as well as the conductive connectivity check of those electronic elements, are performed by having a test probe contact the top part of the bump electrode.
However, contacting the top part of the bump electrode with the test probe involves the problem of the top part thereof being scratched off.
A known bump electrode is formed to have an adequate thickness with an Au electroplate. Hence, even when the top part of the bump electrode is scratched off by the contact with the test probe, the conductive connection between the bump electrode and the opposing substrate is severed. In contrast, in the case of the resin bump electrode 10, the conductive film 20 on the surface of the resin projection 12 is formed to be excessively thin. Because of this reason, when the conductive film 20 on the resin bump electrode 10 is scratched off by the contact with the test probe, the conductive connection between the resin bump electrode 10 and the opposing substrate may not be possible.
The solution could be that a testing part is set between the electrode pad 24 and the resin bump electrode 10, and various tests be performed by having the test probe contact the conductive film 20 on the testing part. Yet, in this case, it is not possible to test the entire conductive connectivity status from the electrode pad 24 to the resin bump electrode 10. Even worse, if the conductive film 20 is scratched off at the testing part by the contact with the test probe, the conductive connection between the electrode pad 24 and the resin bump electrode 10 may be cut off.
On the active surface of the semiconductor device, an insulation film 26 composed of brittle material such as silicon oxide, silicon nitride and the like is formed, and on the insulation film 26, the conductive film 20 is formed. Hence, if the test probe contacts the conductive film 20 at the testing part, the insulation film 26 composed of brittle material may be damaged by the shock of the contact.
In order to solve the aforementioned problems, the present invention aims to provide a semiconductor device that enables to prevent the damage from testing, as well as to secure a conductive connection with the opposing substrate.
Furthermore, the invention also aims to provide a circuit substrate, an electro-optic device, and an electronic appliance, that have a highly reliable conductive connection.